The present invention relates to systems for automatically charging the battery of a remote transmitter which is used in a vehicle security system.
Rechargeable batteries used in remote transmitters of vehicle security systems currently have typically 1000 charge/discharge cycles before xe2x80x9cend of life.xe2x80x9d Current methodologies allow for a certain level of discharge before the charging cycle begins. However, if the battery is removed from its charging fixture or field before it is fully charged, charging will not commence until that battery voltage drops below a voltage threshold.
U.S. Pat. No. 6,023,151 discloses a xe2x80x9csmartxe2x80x9d battery method and apparatus including a dynamic end of voltage (EODV) signal for recharging batteries, one that reflects environment, temperature, chemistry, or cycle and provides enhanced runtime and save-to-disk alarm.
U.S. Pat. No. 6,016,047 discloses a battery management system suitable for a xe2x80x9csmartxe2x80x9d battery including a processor and other means for recovery and producing signals based on temperature, and chemistry status.
U.S. Pat. No. 6,011,546 discloses a xe2x80x9csmartxe2x80x9d battery, part of a larger system, including provisions for self-monitoring and signals mobile processor battery charge state, readiness for re-use following charging, and modules user interface.
U.S. Pat. No. 5,870,685 discloses a system for monitoring battery capacity in a mobile station including a plurality of different thresholds which may trigger transmission of a signal for shutdown and recharging.
U.S. Pat. No. 5,754,029 discloses a battery charging apparatus including means for controlling battery charging current via calendars stored in PROM and uses specified event dates as well as a microprocessor for sending messages to an RF modulator.
U.S. Pat. No. 5,606,240 discloses a battery charger for a lithium battery including means for lengthening or shortening battery charging time based on a plurality of thresholds including protection, status, charge and time.
U.S. Pat. No. 5,572,110 discloses a xe2x80x9csmartxe2x80x9d battery charger including a memory for thresholds and parameters, means for automatically controlling the charging operation, and means for optimizing charging based on temperature, time, battery characteristics and requirements.
U.S. Pat. No. 5,847,546 discloses a xe2x80x9csmartxe2x80x9d battery charging system including a memory and a microprocessor for programming charges and means for generating a charging signal that responds to charging status of the battery being charged.
U.S. Pat. No. 5,850,188 discloses an RKE diagnostic system including means for transmitting a plurality of signals regarding operations including charge status of battery and battery condition.
U.S. Pat. No. 5,717,387 discloses a vehicle control system including the ability to reprogram vehicle operation via transmitting signals such as low battery capable of controlling vehicle accessories.
U.S. Pat. No. 4,395,672 discloses an improved timer for a battery charger including an electric controller and includes a plurality of thresholds and parameters that extend charging cycle and to operate automatically.
Inductive (i.e. magnetic) coupling is a means of transferring electrical energy from one part (area) of a circuit to another part without requiring any ohmic (wire) connection. Instead, magnetic flux linkages couple two inductors (coils). The coils must be in close proximity in order to establish sufficient mutual inductance.
An object of the present invention is to provide a system for automatically charging the battery of a remote transmitter for use in a vehicle security system wherein charging/discharging of the battery is performed in such a way to fully utilize maximum, battery-life potential.
Another object of the present invention is to provide a system for automatically charging the battery of a remote transmitter for use in a vehicle security system wherein a predetermined level of discharge is achieved before a charging cycle begins and wherein a full charge cycle is completed before the charging cycle is complete.
Yet still another object of the present invention is to provide a system for automatically charging the battery of a remote transmitter for use in a vehicle security system wherein a determining circuit determines when the battery is fully charged. In one embodiment, a microprocessor of the system monitors or tracks charging time to ensure full charge before the charging cycle is complete, even if the battery is removed from the charging field/charging fixture for a period of time and the later placed back in the field/fixture with a voltage above a predetermined lower voltage limit.
In carrying out the above objects and other objects of the present invention, a charging system for automatically charging a battery of a remote transmitter for use in a vehicle security system having a base station is provided. The charging system includes a voltage monitoring circuit for monitoring voltage of the battery and causing the transmitter to transmit a first signal when the voltage drops below a predetermined lower limit. A charging circuit charges the battery during a charging cycle in response to the first signal when the battery is coupled to the charging circuit for charging. A determining circuit determines when the battery is fully charged and provides a corresponding fully charged signal wherein the charging circuit stops charging the battery in response to the fully charged signal.
The charging circuit may be inductively coupled to the battery during charging.
The voltage monitoring circuit includes a first microprocessor programmed to monitor the voltage of the battery.
The determining circuit may include a charging time monitoring circuit for monitoring the amount of time the battery is coupled to the charging circuit and is being charged thereby and providing the fully charged signal when the time reaches a predetermined amount.
The charging time monitoring circuit may include a second microprocessor programmed to monitor the amount of time that the charging circuit charges the battery to ensure that the battery is fully charged before the charging cycle is complete.
The first signal may be an RF signal.
The first microprocessor may further be programmed to cause the transmitter to transmit the fully charged signal when the battery is fully charged.
The fully charged signal may be an RF signal.
The above objects and other objects, features, and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.